Generally steel cord layers acting as tensile bodies are internally incorporated in rubber crawlers. From the perspective of durability, such steel cord layers normally have a structure of a single rubber covered steel cord wound in a spiral shape.
However, in spiral structure steel cord layers, the steel cord extends at an angle with respect to the crawler circumferential direction, such that shear deformation occurs in response to tension in the crawler circumferential direction due to anisotropic elasticity of the steel cord layer.
The rubber crawler, trained between the wheels of a machine body under a specific tension, is affected by the shear deformation of the steel cord layer and deforms, resulting in slippage in the crawler width direction (referred to below as “lateral slippage” where appropriate) as the crawler revolves (circulates) between the wheels on which it is trained.
Frequently encountered approaches to suppress lateral slippage of the rubber crawler include adjusting the attachment of the wheels (wheel alignment), providing the rubber crawler with guide projections that guide the rotation direction of the wheels, providing a bias ply that undergoes shear deformation in a direction to cancel out the shear deformation of the steel cord layer, and the like.
In a rubber crawler described in Japanese Utility Model Gazette (JP-Y) No. 2562202, a bias cord layer (bias ply) including a bias cord extending at an angle with respect to the crawler circumferential direction is provided at the crawler circumferential outside of a steel cord layer. Shear deformation of the bias cord layer cancels out shear deformation of the steel cord layer, suppressing lateral slippage during travel.